These annoyed me also as well as the voice command button.
There is a simple fix for this. Take a small flat bladed screwdriver (something not sharp) and pry up on the buttons to remove all that offend. In the hole, you will see the membrane switch, that is the actual button. It sticks up a little, like a blister. Turn over a rubber button and you will see a smaller, round little protrusion. That is what is really pressing on this membrane switch. Now you have a choice:
If you want to reduce the chance of pressing it accidentally, get a cutting board and a sharp knife from the kitchen and cut off the protrusion, even with the rest of the rubber button. Using a sharp kitchen knife was the ticket to a nice clean, straight cut.
If you want it to not work again, take a pointy Exacto hobby knife like I did, and make plunging cuts all around the protrusion in about the same diameter as the actual membrane switch. Very much like you do when cutting out the first slice of pie from a pan. Go all the way around at an angle because you are going to extract a little plug in the shape of a classic engagement ring diamond, pointy on the bottom where your knife points are meeting. You will then return and pretty easily cut it completely out. When done reinstall the rubber button. It will sit lower and stay in place but will look the same otherwise. If you try and press it and nothing happens, you did it right.
For me, it is very satisfying to know they are dead. If you ever wanted to, you could probably glue a small replacement nub back on there with silicone or just replace the rubber buttons. Where you would get them or why you would ever want them again is beyond me. Good riddance to virtually the only major idiocy with my Roku's.